package org.apache.lucene.index;

/**
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import java.io.IOException;

final class SegmentMergeInfo {
	Term term;
	int base;
	TermEnum termEnum;
	IndexReader reader;
	private TermPositions postings; // use getPositions()
	private int[] docMap; // use getDocMap()

	SegmentMergeInfo(int b, TermEnum te, IndexReader r) throws IOException {
		base = b;
		reader = r;
		termEnum = te;
		term = te.term();
	}

	// maps around deleted docs
	int[] getDocMap() {
		if (docMap == null) {
			// build array which maps document numbers around deletions
			if (reader.hasDeletions()) {
				int maxDoc = reader.maxDoc();
				docMap = new int[maxDoc];
				int j = 0;
				for (int i = 0; i < maxDoc; i++) {
					if (reader.isDeleted(i))
						docMap[i] = -1;
					else
						docMap[i] = j++;
				}
			}
		}
		return docMap;
	}

	TermPositions getPositions() throws IOException {
		if (postings == null) {
			postings = reader.termPositions();
		}
		return postings;
	}

	final boolean next() throws IOException {
		if (termEnum.next()) {
			term = termEnum.term();
			return true;
		} else {
			term = null;
			return false;
		}
	}

	final void close() throws IOException {
		termEnum.close();
		if (postings != null) {
			postings.close();
		}
	}
}
